DAC8408FS Analog Devices Inc, DAC8408FS Datasheet - Page 12

• Manufacturer Part Number: DAC8408FS
• Description: IC DAC 8BIT QUAD W/MEMORY 28SOIC
• Manufacturer: Analog Devices Inc

Specifications of DAC8408FS

• Rohs Status: RoHS non-compliant
• Settling Time: 190ns
• Number Of Bits: 8
• Data Interface: Parallel
• Number Of Converters: 4
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Power Dissipation (max): -

DAC8408
SINGLE SUPPLY, VOLTAGE OUTPUT OPERATION
The DAC8408 can be connected with a single +5 V supply to
produce DAC output voltages from 0 V to +1.5 V. In Figure 8,
the DAC8408 R-2R ladder is inverted from its normal connec-
tion. A +1.500 V reference is connected to the current output pin
4 (I
output. Instead of a normal current output, the R-2R ladder out-
puts a voltage. The OP-490, consisting of four precision low
power op amps that can operate its inputs and outputs to zero
volts, buffers the DAC to produce a low impedance output volt-
age from 0 V to +1.5 V full-scale. Table III shows the code table.
With the supply and reference voltages as shown, better than 1/2
LSB differential and integral nonlinearity can be expected. To
maintain this performance level, the +5 V supply must not drop
below 4.75 V. Similarly, the reference voltage must be no higher
than 1.5 V. This is because the CMOS switches require a mini-
mum level of bias in order to maintain the linearity performance.
OUT 1A
), and the normal V
REF
input pin becomes the DAC
Figure 8. Unipolar Supply, Voltage Output DAC Operation
–12–
Table III. Single Supply Binary Code Table (Refer to Figure 8)
DAC Data Input
1 1 1 1 1 1 1 1
1 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0
0 1 1 1 1 1 1 1
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
MSB
LSB
Analog Output
V
V
V
V
V
V
REF
REF
REF
REF
REF
REF
129
128
127
255
256
256
256
256
256
256
1
0
, +1.4941 V
, +0.7559 V
, +0.7500 V
, +0.7441 V
, +0.0059 V
, 0.0000 V
REV. A